This invention relates generally to tamper evident bags of the type typically fabricated from plastic film and having two opposing bag walls.
Various methods have attained widespread use for sealing bags after they have been loaded with contents. These methods include interlocking fasteners of a non-permanent type which are readily closed and opened by simple manual manipulation, and interlocking fasteners or other closable arrangements which are of a permanent type. These methods carry with them several disadvantages which the present invention solves. Interlocking fasteners of the non-permanent type have the problem of opening unintentionally. This is usually caused by the load of contents exerting force against the side walls of the bag thereby forcing the closure apart. Unintentional opening can also occur in the normal course of handling after the bag has been filled. A further problem with this type of closure is the lack of security associated therewith due to the easy opening nature of the closure. Therefore use of the bags with such a closure is limited to those areas where a secured closure is unnecessary such as in a consumer household setting.
Bags with interlocking closures of the permanent type, currently known in the art, require the use of a tool, either attached to the bag or independent therefrom, in order to open and/or seal the bag. Representative of this is U.S. Pat. No. 3,808,649. Use of such a tool is very inconvenient and awkward to the user and also requires an additional expense, neither of which is necessary with a closure which can be manually opened and closed.
Another type of closure arrangement known in the art is a heat seal which permanently seals the contents into a bag after the bag has been loaded. This method has the disadvantage of requiring heat seal equipment which can be expensive and requires continuous maintenance. Such a method is normally used where the bags are filled prior to shipping. In instances which require shipping empty bags to the ultimate user so that they may fill the bags, such expense associated with heat seal equipment can be prohibitive and the method of closure completely inconvenient and inappropriate for such use.